In half bridge circuits, when a switching element of a one-sided arm turns on from a dead time state, there is a phenomenon in which gate erroneous turning-on occurs (misfiring (erroneous firing)) in another-sided switching element caused by a drain voltage change. This is a problem which can occur in three phase inverter circuits, synchronous-rectification DC/DC converters, etc., for example, used for motor driving.
On the other hand, many research institutions are currently conducting research to develop Silicon Carbide (SiC) devices. Advantages of SiC power devices over Si power devices include low on resistance, high switching speed, high temperature operation, etc.
Moreover, if an energy stored in a negative direction in a capacitance between gate and source resonates when a short-circuit current due to the gate erroneous turning-on converges, re-erroneous turning-on (oscillation) will be caused, and then gate surge and drain surge voltages at that time not only can break down the switching element, but can become a noise source.
Extreme high-speed operation is limited since a portion shared between signal wiring and power wiring is in source wiring when forming a bridge with a discrete device and therefore a gate signal is reduced due to electrification of the source wiring.
On the other hand, in power modules in which gate signal wiring and source signal wiring become longer by separating the signal wiring and the power wiring from each other using source sense wiring and by connecting in parallel a semiconductor chip in order to allow large capacities, since it does not receive an inhibition of gate driving due to electrification of the source wiring if using a switching element which performs high-speed operation, the occurrence of erroneous turning-on and an oscillation triggered by the erroneous turning-on is in particular a problem, and is also an important problem which should be avoided in particular.